U.S. patent application number 11/802643 was filed with the patent office on 2007-12-13 for solid-state imaging apparatus, imaging method, and imaging system.
This patent application is currently assigned to NEC ELECTRONICS CORPORATION. Invention is credited to Yasutaka Nakashiba.
Application Number | 20070285541 11/802643 |
Document ID | / |
Family ID | 38821516 |
Filed Date | 2007-12-13 |
United States Patent
Application |
20070285541 |
Kind Code |
A1 |
Nakashiba; Yasutaka |
December 13, 2007 |
Solid-state imaging apparatus, imaging method, and imaging
system
Abstract
A solid-state imaging apparatus 10 includes a solid-state
imaging device 40, and a color filter 16 constituted of a first
color filter 16a (first filter) and a second color filter 16b
(second filter). The solid-state imaging device 40
photoelectrically converts light incident to a face S1 (first face)
thereof to thereby capture an image of an object to be imaged.
Arranged on the face S1 of the solid-state imaging device 40 is the
first color filter 16a and second color filter 16b. The first color
filter 16a is a filter that allows first wavelength band light to
be selectively transmitted therethrough; the second color filter
16b is a filter that allows second wavelength band light in the
longer wavelength side relative to the first wavelength band to be
selectively transmitted therethrough.
Inventors: |
Nakashiba; Yasutaka;
(Kawasaki, JP) |
Correspondence
Address: |
YOUNG & THOMPSON
745 SOUTH 23RD STREET, 2ND FLOOR
ARLINGTON
VA
22202
US
|
Assignee: |
NEC ELECTRONICS CORPORATION
Kawasaki
JP
|
Family ID: |
38821516 |
Appl. No.: |
11/802643 |
Filed: |
May 24, 2007 |
Current U.S.
Class: |
348/272 ;
348/E9.01 |
Current CPC
Class: |
H04N 9/04551 20180801;
H04N 9/045 20130101; G06K 9/0004 20130101; H04N 5/33 20130101 |
Class at
Publication: |
348/272 |
International
Class: |
H04N 9/04 20060101
H04N009/04; H04N 3/14 20060101 H04N003/14 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 1, 2006 |
JP |
2006-153178 |
Claims
1. A solid-state imaging apparatus comprising: a solid-state
imaging device having a first face incident with light and
converting the light into image information; and a filter arranged
on the first face of the solid-state imaging device, wherein the
filter is composed only a first filter allowing first wavelength
band light to be transmitted therethrough; and a second filter
allowing second wavelength band light to be transmitted
therethrough, said first wavelength band light being different from
said second wavelength band light.
2. The solid-state imaging apparatus according to claim 1, wherein
the light of the first wavelength band is blue light, and the light
of the second wavelength band is red light.
3. The solid-state imaging apparatus according to claim 1, further
comprising: a first light source generating the first wavelength
band light; and a second light source generating the second
wavelength band light.
4. The solid-state imaging apparatus according to claim 3, wherein
the first and second light sources are arranged close to the
solid-state imaging device.
5. The solid-state imaging apparatus according to claim 1, wherein
the solid-state imaging device has a semiconductor substrate and a
light receiving unit arranged in the semiconductor substrate, and
wherein the light receiving unit includes: a first light receiving
unit positioned under the first filter; and a second light
receiving unit positioned under the second filter.
6. The solid-state imaging apparatus according to claim 5, wherein
a plurality of the first light receiving units and a plurality of
the second light receiving units are provided.
7. The solid-state imaging apparatus according to claim 5, wherein
the first and second filters are each distributed in plural
portions on the first face, wherein the plurality of the first
light receiving units are disposed in the respective portions in
which the first filter is distributed, and wherein the plurality of
the second light receiving units are disposed in the respective
portions in which the second filter is distributed.
8. The solid-state imaging apparatus according to claim 1, wherein
the first and second filters are arranged in a regular pattern in a
plan view.
9. The solid-state imaging apparatus according to claim 8, wherein
the first and second filters are arranged in a diagonal lattice
pattern in a plan view.
10. The solid-state imaging apparatus according to claim 8, wherein
the first and second filters are arranged in a slit pattern in a
plan view.
11. The solid-state imaging apparatus according to claim 1, wherein
a object to be imaged is a finger, and wherein the gap between the
first filters, and the gap between the second filters are both
smaller than the gap between concave and convex in fingerprints of
the finger.
12. A solid-state imaging apparatus comprising: a solid-state
imaging device having a first face incident with light and being
constituted to be used to detect at least one of fingerprints and
veins of a finger; and a filter provided on the first face of the
solid-state imaging device to allow the light of first and second
wavelength bands to be transmitted therebetween.
13. The solid-state imaging apparatus according to claim 12,
wherein the light of the first wavelength band is blue light, and
the light of the second wavelength band is red light.
14. An imaging method comprising obtaining by using a solid-state
imaging apparatus according to claim 1, a first image being an
image of the object to be imaged obtained by the first wavelength
band light transmitting through the first filter and then entering
the first face.
15. An imaging method comprising obtaining by using a solid-state
imaging apparatus according to claim 1, a second image being an
image of the object to be imaged obtained by the second wavelength
band light transmitting through the second filter and then entering
the first face.
16. A method of imaging an object comprising: receiving light of a
first wavelength band from the object to thereby produce first
information; receiving light of a second wavelength band from the
object to thereby produce second information; and obtaining a
difference between the first information and the second
information.
17. The imaging method according to claim 16, wherein in the step
of receiving the first and second informations, imaging is
performed while the object is moved in an intra-surface direction
of a first face incident with the light of the first wavelength
band the light of the first wavelength band.
18. The imaging method according to claim 16, wherein the object is
a finger, and wherein the difference image corresponds to an image
of vein of the finger.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a solid-state imaging
apparatus, and an imaging method and imaging system using the
same.
[0003] 2. Description of the Related Art
[0004] As a conventional solid-state imaging apparatus, there has
been one disclosed in Japanese Patent Laid-Open No. 2000-217803,
for example. The solid-state imaging apparatus described in this
document is provided with many light receiving units
two-dimensionally arranged, and captures an image of fingerprints
of a finger which contacts a predetermined surface. In addition to
Japanese Patent Laid-Open No. 2000-217803, technical documents of
conventional art relating to the present invention includes
Japanese Patent Laid-Open No. 2004-234040.
[0005] The present inventor has recognized as follows. In the
solid-state imaging apparatus of Japanese Patent Laid-Open No.
2000-217803, although an element (for example, fingerprints of a
finger) on the surface of an object to be imaged can be imaged, an
element (for example, veins of a finger) in the interior of an
object to be imaged cannot be imaged.
SUMMARY
[0006] A solid-state imaging apparatus according to the present
invention includes: a solid-state imaging device having a first
face incident with light and converting the light into image
information; and a filter arranged on the first face of the
solid-state imaging device, wherein the filter is composed only of
a first filter allowing first wavelength band light to be
transmitted therethrough; and a second filter allowing second
wavelength band light to be transmitted therethrough, said first
wavelength band light being different from said second wavelength
band light.
[0007] This solid-state imaging apparatus includes the first and
second filters that allow light of a different wavelength band to
be selectively transmitted therethrough. As a result, an image
(first image) obtained by shorter wavelength light, i.e., light
transmitting through the first filter contains a substantial amount
of information on the surface element of the object to be imaged.
Meanwhile, an image (second image) obtained by longer wavelength
light, i.e., light transmitting through the second filter contains
information on the internal element of the object to be imaged as
well as the information on the surface element. Accordingly, when a
difference between the first image and the second image is
calculated, an image of the internal element of the object to be
imaged can be obtained.
[0008] An imaging method according to the present invention
includes: receiving light of a first wavelength band from the
object to thereby produce first information; receiving light of a
second wavelength band from the object to thereby produce second
information; and obtaining a difference between the first
information and the second information.
[0009] In this imaging method, using the solid-state imaging
apparatus of the present invention, the first and second images are
obtained. Further, the difference image between these images is
obtained. As a result, a clear image of the internal element of the
object to be imaged can be obtained.
[0010] An imaging system according to the present invention
includes: the solid-state imaging apparatus; and a difference
calculation unit calculating a difference image between a first
image being an image of the object to be imaged obtained by the
first wavelength band light transmitting through the first filter
and then entering the first face and a second image being an image
of the object to be imaged obtained by the second wavelength band
light transmitting through the second filter and then entering the
first face.
[0011] This imaging system is provided with the solid-state imaging
apparatus of the present invention and the difference calculation
means. Accordingly, the first and second images can be obtained by
the solid-state imaging apparatus, and the difference image between
these images can be obtained by the difference calculation means.
As a result, a clear image of the internal element of the object to
be imaged can be obtained.
[0012] According to the present invention, there can be implemented
the solid-state imaging apparatus, imaging method, and imaging
system capable of obtaining a clear image of the internal element
of an object to be imaged.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The above and other objects, advantages and features of the
present invention will be more apparent from the following
description of certain preferred embodiments taken in conjunction
with the accompanying drawings, in which:
[0014] FIG. 1 is a block diagram illustrating one embodiment of an
imaging system according to the present invention;
[0015] FIG. 2 is a cross-sectional view illustrating one embodiment
of a solid-state imaging apparatus according to the present
invention;
[0016] FIG. 3 is a plan view illustrating the solid-state imaging
apparatus of FIG. 2;
[0017] FIG. 4 is a plan view for explaining one embodiment of an
imaging method according to the present invention;
[0018] FIG. 5 is a view for explaining a first and second image and
a difference image therebetween;
[0019] FIG. 6 is a plan view illustrating a solid-state imaging
apparatus according to a variation of the embodiment;
[0020] FIG. 7 is a plan view for explaining an example of imaging
method using the solid-state imaging apparatus of FIG. 6; and
[0021] FIG. 8 is a cross-sectional view illustrating a solid-state
imaging apparatus according to another variation of the
embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] The invention will be now described herein with reference to
illustrative embodiments. Those skilled in the art will recognize
that many alternative embodiments can be accomplished using the
teachings of the present invention and that the invention is not
limited to the embodiments illustrated for explanatory purposes. In
explaining the drawings, the same reference numerals are applied to
identical parts, and repeated explanation thereof is omitted.
[0023] FIG. 1 is a block diagram illustrating one embodiment of an
imaging system according to the present invention. An imaging
system 1 includes a solid-state imaging apparatus 10 and a
difference calculation unit 20. The difference calculation unit 20
is difference calculation means for calculating a difference image
between a first and second image. The first and second image will
be described later. The difference calculation unit 20 is a
computer terminal, for example.
[0024] FIG. 2 is a cross-sectional view illustrating the
solid-state imaging apparatus 10 being one embodiment of the
solid-state imaging apparatus according to the present invention.
Also FIG. 3 is a plan view illustrating the solid-state imaging
apparatus 10. A cross-sectional view along the line II-II in FIG. 3
corresponds to FIG. 2.
[0025] The solid-state imaging apparatus 10 includes a solid-state
imaging device 40, and a color filter 16 constituted of a first
color filter 16a (first filter) and a second color filter 16b
(second filter). The solid-state imaging device 40 has a
semiconductor substrate 12 and an interconnect layer 30 formed
thereon. According to the present embodiment, the semiconductor
substrate 12 is a p-type silicon substrate. Interconnect s (not
illustrated) are formed in the interconnect layer 30. The
solid-state imaging device 40 photoelectrically converts light
incident to a face S1 (first face) thereof to thereby take an image
of an object to be imaged. Here, the face S1 of the solid-state
imaging device 40 is equal to the surface of the interconnect layer
30.
[0026] A plurality of light receiving units 14 are formed in the
semiconductor substrate 12. More specifically, the light receiving
units 14 are arranged in the superficial layer of the semiconductor
substrate 12. According to the present embodiment, the light
receiving units 14 are an n-type impurity diffusion layer. The
light receiving units 14 constitute a photodiode along with the
adjoining semiconductor substrate 12.
[0027] Arranged on the face S1 of the solid-state imaging device 40
is the color filter 16 constituted of the first color filter 16a
and second color filter 16b. The first color filter 16a is a filter
that allows first wavelength band light to be selectively
transmitted therethrough; the second color filter 16b is a filter
that allows second wavelength band light in the longer wavelength
side relative to the first wavelength band to be selectively
transmitted therethrough. According to the present embodiment, the
first wavelength band light is blue light; the second wavelength
band light is red light.
[0028] According to the present embodiment, the first color filter
16a and second color filter 16b are, as illustrated in FIG. 3,
arranged in a regular pattern in a plan view, and more
specifically, arranged in a diagonal lattice pattern. Here, the
expression "arrangement in a diagonal lattice pattern" means that
the first color filter 16a and second color filter 16b are
alternately arranged both longitudinally and laterally with one
piece of the first color filter 16 adjacent to one piece of the
second color filter 16b. Accordingly, the first color filter 16a
and second color filter 16b are each distributed in plural portions
on the face 1.
[0029] The light receiving unit 14 includes a light receiving unit
14a (first light receiving unit) positioned under the first color
filter 16a, and a light receiving unit 14b (second light receiving
unit) positioned under the second color filter 16b. In each portion
in which the first color filters 16a are arranged, there are
arranged one or more light receiving units 14a. Similarly, in each
portion in which the second color filters 16b are arranged, there
are arranged one or more light receiving units 14b;
[0030] The solid-state imaging apparatus 10 is further provided
with a light source 42a (first light source) and a light source 42b
(second light source). These light sources 42a and 42b are arranged
close to the solid-state imaging device 40. The light source 42a is
a light source that generates the first wavelength band light; the
light source 42b is a light source that generates the second
wavelength band light. That is, according to the present
embodiment, the light sources 42a and 42b are a blue light source
and a red light source, respectively. However, the light sources
42a and 42b may be both a white light source.
[0031] As one embodiment of the imaging method according to the
present invention, an exemplary operation of the imaging system 1
will be described with reference to FIG. 4. Referring to FIG. 4, a
finger 90 being an object to be imaged is brought into contact to
the surface of the solid-state imaging apparatus 10 (to the surface
of the first color filter 16a and second color filter 16b). When
light from the light sources 42a and 42b enters the finger 90, the
light transmitting therethrough enters the face Si of the
solid-state imaging device 40.
[0032] Then, in the portion in which the second color filter 16b is
arranged, red light having a longer wavelength is transmitted
therethrough, and thus an image having a small signal difference
between the fingerprint image and veins image is obtained.
Consequently, as shown in the left diagram of FIG. 5, an image
(second image) 96 of a fingerprint 92 and veins 94 is obtained.
This image is an image of the object to be imaged obtained by the
red light transmitting through the second color filter 16b and then
entering the face 1. Meanwhile, in the portion in which the first
color filter 16a is arranged, blue light having a shorter
wavelength is transmitted therethrough, and thus an image having a
large small signal difference between fingerprint image and veins
image is obtained. Consequently, as shown in the central diagram of
FIG. 5, an image (first image) 98 of the fingerprint 92 and veins
94 is obtained. This image is an image of the object to be imaged
obtained by the blue light transmitting through the first color
filter 16a and then entering the face 1.
[0033] In this manner, using the solid-state imaging apparatus 10,
the first and second images are obtained. Thereafter, a difference
image 100 being the difference between these images is calculated
by the difference calculation unit 20. In the present embodiment,
as shown in the right diagram of FIG. 5, this difference image 100
corresponds to the image of the veins 94. It is noted that, when
the object to be imaged is as with this embodiment a finger, the
gap between the first color filters 16a, and the gap between the
second color filters 16b (the gaps being both a gap d1 in FIG. 2)
must be both smaller than the gap between concave and convex in
fingerprints of finger.
[0034] The advantageous effect of the present embodiment will be
described. According to the present embodiment, there are provided
the first color filter 16a and second color filter 16b that allow
light of a different wavelength band to be selectively transmitted.
Accordingly, the image (first image) 98 obtained by light having a
shorter wavelength, i.e., light transmitting through the first
color filter 16a contains much information on the surface element
of an object to be imaged. Meanwhile, the image (second image) 96
obtained by light having a longer wavelength, i.e., light
transmitting through the second color filter 16b contains
information on the internal element of the object to be imaged as
well as the surface element thereof. Consequently, when a
difference between the first image 98 and second image 96 is
calculated, a clear image of the internal element of the object to
be imaged can be obtained. When the object to be imaged is as with
the above example a finger, an image of the finger veins being the
internal element can be obtained, and thus veins authentication can
be performed by the imaging system 1. In addition, with the present
embodiment, the images of fingerprints and veins can be
simultaneously taken.
[0035] The light receiving unit 14 includes the light receiving
unit 14a positioned under the portion in which the first color
filter 16a is arranged, and a light receiving unit 14b positioned
under the portion in which the second color filter 16b is arranged.
Consequently, the light from the object to be imaged, transmitting
through the first color filter 16a is received by the light
receiving unit 14a and at the same time, the light from the object
to be imaged, transmitting through the second color filter 16b is
received by the light receiving unit 14b, whereby the first and
second images can be obtained with high sensitivity.
[0036] When a plurality of the light receiving units 14a are
arranged in the respective portions in which the first color filter
16a is arranged and at the same time, a plurality of the light
receiving units 14b are arranged in the respective portions in
which the second color filter 16b is arranged, then the first and
second images can be obtained with high sensitivity.
[0037] The first color filter 16a and second color filter 16b are
arranged in a diagonal lattice pattern in a plan view. Accordingly,
when the object to be imaged is in a static condition, also, the
first and second images can be properly obtained.
[0038] In Japanese Patent Laid-Open No. 2004-234040, there has been
described an individual authentication apparatus in which an
infra-red filter is arranged between a finger being an object to be
imaged and an image sensor. However, a plurality of filters that
transmit light of a different wavelength band are not provided.
Thus, in the individual authentication apparatus of this document,
it is not possible to properly capture the image of both
fingerprints and veins. Also, noise (fingerprint image when a veins
image is captured) cannot be eliminated. In contrast, according to
the present embodiment, as illustrated in FIG. 5, a veins image is
obtained by calculating a difference between an image of
fingerprints and veins and an image of fingerprints. Accordingly,
when the difference therebetween is calculated, the noise can be
eliminated naturally.
[0039] The solid-state imaging apparatus, imaging method, and
imaging system according to the present invention are not limited
to the above described embodiment, and various variations are
possible. For example, in the above embodiment, there is shown the
example in which the first color filter 16a and second color filter
16b are arranged in a diagonal lattice pattern. However, the first
color filter 16a and second color filter 16b may be, as illustrated
in FIG. 6, arranged in a slit pattern. Here, the expression
"arrangement in a slit pattern" means that a line of the first
color filters 16a and a line of the second color filters 16b are
alternately arranged. In this case, imaging is preferably performed
while the object to be imaged is moved in an intra-surface
direction of the face S1. FIG. 7 illustrates a way in which imaging
is performed while a finger 90 being an object to be imaged is
moved in a direction (vertical direction in FIG. 7) perpendicular
to the longitudinal direction of the slit. Since imaging is
performed while the object to be imaged is moved, even when the
imaging area (the area in which the light receiving units 14a and
14b are arranged) is small, an image of a large part of the object
to be imaged can be taken. This contributes to the smaller imaged
area and even the smaller size of the entire solid-state imaging
apparatus. In the solid-state imaging apparatus 10 illustrated in
FIGS. 2 and 3, also, imaging may be performed while the object to
be imaged is moved.
[0040] In the above described embodiment, as an example of the
first wavelength band light and the second wavelength band light,
there are shown blue light and red light, respectively. However,
the light combination is not limited thereto, and another
combination is also possible such as: light having wavelength close
to blue light and light having wavelength close to red light; green
light and red light; or green light and near-infrared light.
[0041] Further, in the above described embodiment, p-type
semiconductor substrate and n-type light receiving unit are shown
as an example, but n-type semiconductor substrate and p-type light
receiving unit are also possible. Further, the front-face incident
type solid-state imaging apparatus is shown as an example, but a
rear-face incident type solid-state imaging apparatus is also
possible, as illustrated in FIG. 8. Referring to FIG. 8, the rear
face S2 of the solid-state imaging apparatus 40 is the first face.
More specifically, in the solid-state imaging apparatus 40 in FIG.
8, light incident to the rear face S2 is photoelectrically
converted to take an object image. Here, the rear face S2 of the
solid-state imaging apparatus 40 is equal to the rear face of the
semiconductor substrate 12. Further, the present invention may be
applied to a CCD (Charge Coupled Device) type solid-state imaging
apparatus.
[0042] It is apparent that the present invention is not limited to
the above embodiments, but may be modified and changed without
departing from the scope and spirit of the invention.
* * * * *